Here's the way to install Steem software to your Mac with just two commands. Actually, only one if you have Homebrew already installed.
Step 1: Install Homebrew
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
The script explains what it will do and then pauses before it does it.
Step 2: Install Steem wallet
brew install TigerND/core/steem